There have been a number of recent "accidents" involving escalators, in which a passenger on the escalator has had his shoe or boot become trapped between the moving escalator step and the stationary side skirt defining the side walls of the escalator passageway. These accidents usually arise when the passenger, wearing footwear which has a rubber sole, places his foot down on the escalator step over at the side, so that part of the sole projects beyond the side of the escalator step and comes into frictional contact with the side skirt of the escalator passageway. As the escalator step moves upwardly with respect to the side skirt, there is a "snubbing" action which attempts to draw the edge of the sole of the shoe down into the crack between the escalator step and the side skirt. This can result in serious damage to the foot of the person becoming so entrapped, and escalator owners have been sued for damages in connection with some of these accidents.
In order to minimize or eliminate the risk of such shoe entrapment on escalators, certain approaches have been utilized, which form part of the prior art.
One approach involves re-designing the escalator step itself, so that the outside upstanding teeth are raised higher than the remaining teeth in the middle portion of the escalator step. It is well known that escalator steps are defined at their top surface by a plurality of upstanding, parallel teeth in a comb-like arrangement, all running parallel to the direction in which the escalator is moving. This allows a structure at the top and bottom of the escalator which ensures that there will be no entrapment of shoes or the like at the top and bottom where the escalator step disappears under the main floor. The normal construction involves a comb-like scouring unit which has downwardly projecting teeth extending into the spaces or grooves between the upstanding teeth on the escalator step.
While the approach previously mentioned, that of raising the outside one or two escalator teeth to a level above the rest of the teeth, is found to work satisfactorily in many cases, it does not provide a solution for the existing escalator installations. The effectiveness of this prior art approach is to make it uncomfortable for the passenger to leave his foot on the raised teeth, thus prompting him automatically to move the foot inwardly away from the side skirt.
Another approach to this problem is exemplified in U.S. Pat. No. 4,236,623, issued on Dec. 2, 1980 to Duane B. Ackert. This patent relates to inserts adapted to be interfitted with the outside one or two upstanding teeth of an escalator step, in order to provide a raised region which will prompt a passenger to remove his foot from the side area. However, this prior art insert device is complex and utilizes a considerable amount of material. Moreover, it does not include the capability of allowing the release of a passenger's shoe if that shoe should in fact become caught between the insert and the side skirt.